From: Michael Jeanson Date: Tue, 6 Apr 2021 16:29:36 +0000 (-0400) Subject: Move getcpu.h to 'lib/lttng-ust/' X-Git-Tag: v2.13.0-rc1~122 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=247c2ecd8e17ab02996e45cfa1be254b04161210;p=lttng-ust.git Move getcpu.h to 'lib/lttng-ust/' Move getcpu.h from 'common/ringbuffer' to 'lib/lttng-ust', the implementation is there and it provides some liblttng-ust symbols to other components unrelated to the ringbuffer. * Namespace internal symbols for clarity * Add comments to the code. Change-Id: I93da098dc9f90aa6324ad1ac36eaba1c660f0f64 Signed-off-by: Michael Jeanson Signed-off-by: Mathieu Desnoyers --- diff --git a/src/common/Makefile.am b/src/common/Makefile.am index 619276ed..2ab4bfdc 100644 --- a/src/common/Makefile.am +++ b/src/common/Makefile.am @@ -90,7 +90,6 @@ libringbuffer_la_SOURCES = \ ringbuffer/frontend.h \ ringbuffer/frontend_internal.h \ ringbuffer/frontend_types.h \ - ringbuffer/getcpu.h \ ringbuffer/nohz.h \ ringbuffer/rb-init.h \ ringbuffer/ring_buffer_backend.c \ diff --git a/src/common/counter/counter-api.h b/src/common/counter/counter-api.h index 81bb551b..3465d5dc 100644 --- a/src/common/counter/counter-api.h +++ b/src/common/counter/counter-api.h @@ -16,7 +16,7 @@ #include #include #include "common/bitmap.h" -#include "common/ringbuffer/getcpu.h" +#include "lib/lttng-ust/getcpu.h" /* * Using unsigned arithmetic because overflow is defined. diff --git a/src/common/ringbuffer/getcpu.h b/src/common/ringbuffer/getcpu.h deleted file mode 100644 index 52c74413..00000000 --- a/src/common/ringbuffer/getcpu.h +++ /dev/null @@ -1,104 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2011 Mathieu Desnoyers - */ - -#ifndef _LTTNG_GETCPU_H -#define _LTTNG_GETCPU_H - -#include -#include -#include - -void lttng_ust_getcpu_init(void) - __attribute__((visibility("hidden"))); - -extern int (*lttng_get_cpu)(void) - __attribute__((visibility("hidden"))); - -#ifdef LTTNG_UST_DEBUG_VALGRIND - -/* - * Fallback on cpu 0 if liblttng-ust is build with Valgrind support. - * get_cpu() returns the current CPU number. It may change due to - * migration, so it is only statistically accurate. - */ -static inline -int lttng_ust_get_cpu_internal(void) -{ - return 0; -} - -#else - -/* - * sched_getcpu. - */ -#ifdef __linux__ - -#if !HAVE_SCHED_GETCPU -#include -#define __getcpu(cpu, node, cache) syscall(__NR_getcpu, cpu, node, cache) -/* - * If getcpu is not implemented in the kernel, use cpu 0 as fallback. - */ -static inline -int lttng_ust_get_cpu_internal(void) -{ - int cpu, ret; - - ret = __getcpu(&cpu, NULL, NULL); - if (caa_unlikely(ret < 0)) - return 0; - return cpu; -} -#else /* HAVE_SCHED_GETCPU */ -#include - -/* - * If getcpu is not implemented in the kernel, use cpu 0 as fallback. - */ -static inline -int lttng_ust_get_cpu_internal(void) -{ - int cpu; - - cpu = sched_getcpu(); - if (caa_unlikely(cpu < 0)) - return 0; - return cpu; -} -#endif /* HAVE_SCHED_GETCPU */ - -#elif (defined(__FreeBSD__) || defined(__CYGWIN__)) - -/* - * FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU - * number 0, with the assocated performance degradation on SMP. - */ -static inline -int lttng_ust_get_cpu_internal(void) -{ - return 0; -} - -#else -#error "Please add support for your OS into liblttng-ust/compat.h." -#endif - -#endif - -static inline -int lttng_ust_get_cpu(void) -{ - int (*getcpu)(void) = CMM_LOAD_SHARED(lttng_get_cpu); - - if (caa_likely(!getcpu)) { - return lttng_ust_get_cpu_internal(); - } else { - return getcpu(); - } -} - -#endif /* _LTTNG_GETCPU_H */ diff --git a/src/common/ringbuffer/smp.h b/src/common/ringbuffer/smp.h index 028a66f7..8a96d3d7 100644 --- a/src/common/ringbuffer/smp.h +++ b/src/common/ringbuffer/smp.h @@ -7,7 +7,7 @@ #ifndef _LIBRINGBUFFER_SMP_H #define _LIBRINGBUFFER_SMP_H -#include "getcpu.h" +#include "lib/lttng-ust/getcpu.h" /* * 4kB of per-cpu data available. Enough to hold the control structures, diff --git a/src/lib/lttng-ust/Makefile.am b/src/lib/lttng-ust/Makefile.am index df0ae8d0..3548a9e6 100644 --- a/src/lib/lttng-ust/Makefile.am +++ b/src/lib/lttng-ust/Makefile.am @@ -126,7 +126,8 @@ liblttng_ust_support_la_SOURCES = \ lttng-counter-client.h \ lttng-counter-client-percpu-32-modular.c \ lttng-counter-client-percpu-64-modular.c \ - lttng-clock.c lttng-getcpu.c + lttng-clock.c \ + getcpu.c getcpu.h liblttng_ust_la_SOURCES = diff --git a/src/lib/lttng-ust/getcpu.c b/src/lib/lttng-ust/getcpu.c new file mode 100644 index 00000000..483f8131 --- /dev/null +++ b/src/lib/lttng-ust/getcpu.c @@ -0,0 +1,76 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2014 Mathieu Desnoyers + */ + +#define _LGPL_SOURCE +#include +#include +#include +#include "common/logging.h" +#include +#include + +#include "getenv.h" +#include "lib/lttng-ust/getcpu.h" + +/* Function pointer to the current getcpu callback. */ +int (*lttng_ust_get_cpu_sym)(void); + +static +void *getcpu_plugin_handle; + +/* + * Override the user provided getcpu implementation. + */ +int lttng_ust_getcpu_override(int (*getcpu)(void)) +{ + CMM_STORE_SHARED(lttng_ust_get_cpu_sym, getcpu); + return 0; +} + +/* + * Initialize the getcpu plugin if it's present. + */ +void lttng_ust_getcpu_plugin_init(void) +{ + const char *libname; + void (*getcpu_plugin_init)(void); + + /* If a plugin is already loaded, do nothing. */ + if (getcpu_plugin_handle) + return; + + /* + * If the LTTNG_UST_GETCPU_PLUGIN environment variable is undefined, do + * nothing. + */ + libname = lttng_ust_getenv("LTTNG_UST_GETCPU_PLUGIN"); + if (!libname) + return; + + /* + * Thy to dlopen the getcpu plugin shared object specified in + * LTTNG_UST_GETCPU_PLUGIN. + */ + getcpu_plugin_handle = dlopen(libname, RTLD_NOW); + if (!getcpu_plugin_handle) { + PERROR("Cannot load LTTng UST getcpu override library %s", + libname); + return; + } + dlerror(); + + /* Locate the getcpu plugin init function in the shared object. */ + getcpu_plugin_init = (void (*)(void)) dlsym(getcpu_plugin_handle, + "lttng_ust_getcpu_plugin_init"); + if (!getcpu_plugin_init) { + PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()", + libname); + return; + } + + /* Run the user provided getcpu plugin init function. */ + getcpu_plugin_init(); +} diff --git a/src/lib/lttng-ust/getcpu.h b/src/lib/lttng-ust/getcpu.h new file mode 100644 index 00000000..cac34017 --- /dev/null +++ b/src/lib/lttng-ust/getcpu.h @@ -0,0 +1,119 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2011 Mathieu Desnoyers + */ + +#ifndef _LTTNG_GETCPU_H +#define _LTTNG_GETCPU_H + +#include +#include +#include + +#include + + +/* + * Initialize the getcpu plugin if it's present. + */ +void lttng_ust_getcpu_plugin_init(void) + __attribute__((visibility("hidden"))); + +/* + * Function pointer to the user provided getcpu callback, can be set at library + * initialization by a dlopened plugin or at runtime by a user by calling + * lttng_ust_getcpu_override() from the public API. + */ +extern int (*lttng_ust_get_cpu_sym)(void) + __attribute__((visibility("hidden"))); + +#ifdef LTTNG_UST_DEBUG_VALGRIND + +/* + * Fallback on cpu 0 if liblttng-ust is build with Valgrind support. + * get_cpu() returns the current CPU number. It may change due to + * migration, so it is only statistically accurate. + */ +static inline +int lttng_ust_get_cpu_internal(void) +{ + return 0; +} + +#else + +/* + * sched_getcpu. + */ +#ifdef __linux__ + +#if !HAVE_SCHED_GETCPU +#include +#define __getcpu(cpu, node, cache) syscall(__NR_getcpu, cpu, node, cache) +/* + * If getcpu is not implemented in the kernel, use cpu 0 as fallback. + */ +static inline +int lttng_ust_get_cpu_internal(void) +{ + int cpu, ret; + + ret = __getcpu(&cpu, NULL, NULL); + if (caa_unlikely(ret < 0)) + return 0; + return cpu; +} +#else /* HAVE_SCHED_GETCPU */ +#include + +/* + * If getcpu is not implemented in the kernel, use cpu 0 as fallback. + */ +static inline +int lttng_ust_get_cpu_internal(void) +{ + int cpu; + + cpu = sched_getcpu(); + if (caa_unlikely(cpu < 0)) + return 0; + return cpu; +} +#endif /* HAVE_SCHED_GETCPU */ + +#elif (defined(__FreeBSD__) || defined(__CYGWIN__)) + +/* + * FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU + * number 0, with the assocated performance degradation on SMP. + */ +static inline +int lttng_ust_get_cpu_internal(void) +{ + return 0; +} + +#else +#error "Please add support for your OS into liblttng-ust/compat.h." +#endif + +#endif + +static inline +int lttng_ust_get_cpu(void) +{ + int (*lttng_ust_get_cpu_current)(void) = CMM_LOAD_SHARED(lttng_ust_get_cpu_sym); + + /* + * Fallback to the internal getcpu implementation if no override was + * provided the user. + */ + if (caa_likely(!lttng_ust_get_cpu_current)) { + return lttng_ust_get_cpu_internal(); + } else { + return lttng_ust_get_cpu_current(); + } +} + +#endif /* _LTTNG_GETCPU_H */ diff --git a/src/lib/lttng-ust/lttng-context-cpu-id.c b/src/lib/lttng-ust/lttng-context-cpu-id.c index 900b3c2e..9a70ca52 100644 --- a/src/lib/lttng-ust/lttng-context-cpu-id.c +++ b/src/lib/lttng-ust/lttng-context-cpu-id.c @@ -19,7 +19,7 @@ #include #include #include -#include "common/ringbuffer/getcpu.h" +#include "lib/lttng-ust/getcpu.h" #include #include "context-internal.h" diff --git a/src/lib/lttng-ust/lttng-getcpu.c b/src/lib/lttng-ust/lttng-getcpu.c deleted file mode 100644 index 8d2c944c..00000000 --- a/src/lib/lttng-ust/lttng-getcpu.c +++ /dev/null @@ -1,55 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2014 Mathieu Desnoyers - */ - -#define _LGPL_SOURCE -#include -#include -#include -#include "common/logging.h" -#include -#include -#include - -#include "getenv.h" -#include "common/ringbuffer/getcpu.h" - -int (*lttng_get_cpu)(void); - -static -void *getcpu_handle; - -int lttng_ust_getcpu_override(int (*getcpu)(void)) -{ - CMM_STORE_SHARED(lttng_get_cpu, getcpu); - return 0; -} - -void lttng_ust_getcpu_init(void) -{ - const char *libname; - void (*libinit)(void); - - if (getcpu_handle) - return; - libname = lttng_ust_getenv("LTTNG_UST_GETCPU_PLUGIN"); - if (!libname) - return; - getcpu_handle = dlopen(libname, RTLD_NOW); - if (!getcpu_handle) { - PERROR("Cannot load LTTng UST getcpu override library %s", - libname); - return; - } - dlerror(); - libinit = (void (*)(void)) dlsym(getcpu_handle, - "lttng_ust_getcpu_plugin_init"); - if (!libinit) { - PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()", - libname); - return; - } - libinit(); -} diff --git a/src/lib/lttng-ust/lttng-ust-comm.c b/src/lib/lttng-ust/lttng-ust-comm.c index 995c78ff..219ef5d2 100644 --- a/src/lib/lttng-ust/lttng-ust-comm.c +++ b/src/lib/lttng-ust/lttng-ust-comm.c @@ -50,7 +50,7 @@ #include "common/ringbuffer/rb-init.h" #include "lttng-ust-statedump.h" #include "clock.h" -#include "common/ringbuffer/getcpu.h" +#include "lib/lttng-ust/getcpu.h" #include "getenv.h" #include "ust-events-internal.h" #include "context-internal.h" @@ -2125,7 +2125,7 @@ void lttng_ust_init(void) lttng_ust_tp_init(); lttng_ust_init_fd_tracker(); lttng_ust_clock_init(); - lttng_ust_getcpu_init(); + lttng_ust_getcpu_plugin_init(); lttng_ust_statedump_init(); lttng_ust_ring_buffer_clients_init(); lttng_ust_counter_clients_init();